86 THE BOTANICAL MAGAZINE. LVoi. xxxiv. Xo. 402. 



plants, with the single exception of Schreiner and Skinner's solution, 

 which lacks magnesium. Although the growth criteria used by Shive 

 were not the same as those employed in the present study, it is never- 

 theless interesting to determine about where on Shive's scale of com- 

 parative values the three very best solutions without potassium may 

 be inserted. This may be done in a roughly approximate way by 

 considering that Shive's best solution had a value of 1.74 on his 

 scale and that Morita's three best solutions (without potassium) are 

 classed as five-sevenths as good as Shive's best by the present test. 

 Now, five-sevenths of 1.74 is 1.24. which may be regarded as the 

 approximate value, on the Shive scale, for each of Morita's three 

 best solutions. Examining Shive's list, we find that Morita's three 

 best solutions (1.24) apparently lie between Tollens' solution (1.23) 

 and Schreiner and Skinner's solution (1.26). In a similar manner it 

 may be calculated that Morita's solution FR5S1 (1.08) lies between 

 Detmer's solution (1.03) and Tollens' solution (1,23). Other solu- 

 tions of the present series may be located on Shive's scale in a 

 like way. 



It therefore seems probable that, for the first three weeks of 

 growth of this wheat, after germination to a height of 3 cm., it is 

 possible to obtain better development with a solution in which no 

 potassium is used (but in which the salts are employed in proper 

 proportions) than can be obtained from any one of several of the 

 poorer complete solutions that have been employed by physiologists 

 (Sachs, Schimper, Detmer, Tollens— see Shive's paper, 1916). The 

 three best incomplete solutions of the present study seem to be each 

 about equal in physiological value to Tollens' complete solution and 

 to Schreiner and Skinner's incomplete solution (without magnesium). 

 The last-mentioned writers appear to have regarded their solution as 

 a sort of standard for comparison, and they used young wheat plants, 

 so that it is particularly important to emphasize that as good growth 

 of these plants may be expected from either of Morita's three best 

 solutions as from Schreiner and Skinner's solution. 



It is of course improbable that any solution treatment not involv- 

 ing potassium may be found that will produce good growth to 

 maturity, but such an assumption cannot be seriously adopted with- 

 out very much more comprehensive experimental study than has ever 

 yet been attempted. The outcome of the present preliminary investiga- 

 tion once more emphasizes the fact that salt proportions and total 

 concentration must be carefully considered whenever the problems of 

 the mineral nutrition of plants are dealt with. The experiments com- 



